256393905 has 16 divisors (see below), whose sum is σ = 421318464. Its totient is φ = 133047360.

The previous prime is 256393877. The next prime is 256393927. The reversal of 256393905 is 509393652.

It is not a de Polignac number, because 256393905 - 2⁵ = 256393873 is a prime.

It is a super-2 number, since 2×256393905² = 131475669042298050, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 230431 + ... + 231540.

It is an arithmetic number, because the mean of its divisors is an integer number (26332404).

Almost surely, 2^256393905 is an apocalyptic number.

It is an amenable number.

256393905 is a deficient number, since it is larger than the sum of its proper divisors (164924559).

256393905 is a wasteful number, since it uses less digits than its factorization.

256393905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462016.

The product of its (nonzero) digits is 218700, while the sum is 42.

The square root of 256393905 is about 16012.3047997470. The cubic root of 256393905 is about 635.2859232760.

The spelling of 256393905 in words is "two hundred fifty-six million, three hundred ninety-three thousand, nine hundred five".